The second-quarter results mark the third consecutive quarterly increase in optimism about the U.S. economy, reaching one of the highest levels since the Great Recession, the survey says. The percent of business owners feeling more optimistic this quarter increased nine percentage points from the previous quarter and 17 from the fourth quarter of 2012, according to the survey.

"As we get further and further away from the recession, companies are more confident that they survived, that they touched the bottom and bounced back up," says Ken Esch, a partner with the PricewaterhouseCoopers Private Company Services practice. Recent improvements in the housing and labor markets have underscored that confidence in the recovery, Esch says. Looking forward, trends in optimism are "pointing upward," he says.

Meanwhile, U.S. businesses are less confident about the global economy. Only 39 percent of U.S. companies that do business abroad report optimism about the world economy, the report finds.

"As momentum builds around optimism in the U.S. economy, we're finding that this translates into more companies looking to reinvest in their growth plans," says Esch. Indeed, 57 percent of business owners plan to hire over the coming 12 months, the survey says. That represents a five-percentage-point increase from the previous quarter.

U.S. companies doing business internationally may be dealing with higher costs but are also more likely to reinvest in the business, the report says. Companies doing business overseas plan to make more capital investments and hire more than their peers that are only doing business domestically. "For these companies, maintaining a presence in key growth markets abroad is a priority, and so they are adapting to trends such as rising labor and shipping costs in China, rather than shying away from opportunities in global markets," says Esch.

Catherine Clifford

Catherine Clifford is senior entrepreneurship writer at CNBC. She was formerly a senior writer at Entrepreneur.com, the small business reporter at CNNMoney and an assistant in the New York bureau for CNN. Clifford attended Columbi...